Ioana Bidian • Joi, 01.06.2023
The grapevine can have five different types of flowers, of which only two types are characteristic of noble vine varieties cultivated in vineyards.
In most noble vine varieties, fruit-bearing varieties, the flowers are hermaphroditic, morphologically and functionally normal, which means they have both well-developed androecium (male reproductive organs) and gynoecium (female reproductive organs). The gynoecium is centrally located, while the stamens are arranged peripherally, surrounding the gynoecium. They are directed upwards and, in most cases, exceed the gynoecium in height.
What is very interesting is that the grapevine's flowering and petal opening ensure the self-fertilization of the flowers. The petals of the flower remain attached at the top, unfold from the base, and this is the moment when pollen is shaken off from the stamens onto the pistil, thus achieving self-fertilization. The petals fall to the ground in the form of small green stars.
This is the grapevine's adaptation for self-fertilization and the formation of grape berries. Why did the grapevine need such an adaptation? Because grapevine flowers have no scent, a small amount of pollen, and thus do not attract insects for pollination.
The second type of flower found in noble varieties is functionally female hermaphroditic, meaning it only has a normally developed pistil while the stamens are curved downwards and contain sterile pollen. Although the flower still opens in a hood-like shape, the pistil cannot be pollinated. Varieties with these types of flowers require external pollinators to achieve cross-pollination.
The other three types of flowers are mainly found in rootstocks derived from various species of the genus Vitis.
The flowers can be functionally male hermaphroditic, in which the androecium is normally developed but the gynoecium is poorly developed. These flowers have fertile pollen, but the atrophied ovary cannot be fertilized.
There are also male or female unisexual flowers, which are also found in rootstocks that have either only androecium or only gynoecium, and therefore cannot self-fertilize.
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